I am revising the Nmea4Wifi tool. I already posted here that the tool (a Windows Program) has 2 aims:
- to setup the Nmea4Wifi multiplexer
- to test transmission and reception of Nmea 183 sentences
I will describe how it works and I ask you to read this again after viewing the video below. The tool has 2 parts. One for transmitting sentences that are stored in a text file and another part to receive sentences and record them into a file.
The Transmitting Part has what I called 3 Targets (or destinations): COM, UDP and TCP. With a simple "usb to serial" cable adapter you can feed any of the Nmea183 input ports of a multiplexer or any Nmea183 listener. For that you direct the sentences to the COM port. You can also send sentences by wifi from your computer to any of my multiplexers either by UDP (eg using the UDP protocol) or TCP. For that it is imperious that your computer is connected to the wifi network created by the multiplexer. The file that contains the sentences can be transmitted periodically or just once. There is check box that if set means that the transmissions stops when you reach the end of the file, You can also set the time interval between the transmitted sentences. In the video this time is 100 ms which means that about 10 sentences are sent in 1 second. You can also filter the sentences, but this was not explored in the video. In order to start the transmission you press the button "Resume". The transmission starts immediately in the case of COM and UDP targets as there are just sent and forgotten. In the case of the TCP target the transmission only starts if the multiplexer is set to receive TCP packets. This is so because the TCP protocol is a connection protocol. The sender and the receiver much establish a connection and then the transmission starts. If there are errors, the receiver asks the sender to repeat the lost packets.
The Receiving Part is very similar. In these case there are 3 Sources: COM, UDP and TCP. The UDP source is only specified by a port number. The file that receives the sentences is empty in the video. To start the reception you should press "Resume" as in the previous case. However you only get sentences if someone is sending them. If you are receiving sentences by wifi, your computer needs to be connected to the multiplexer. During the development of the tool, many times I thought that something was wrong to discover that the cause was that my computer was connected to home wifi network instead of being connected to the multiplexer AP (Access Point).
This is a picture of the multiplexer I was using during the recording of the video. It was the Nmea4Wifi Large version with just a USB cable connected to power it up. I could try to send and receive trough USB (in the case of this multiplexer) but I limited the video to the case of sending sentences trough UDP and receiving through TCP. So all the multiplexer check boxes were unchecked except the case "UDP > TCP". I used the ports 2000 for UDP and 3000 for TCP. These ports should be the same in both ends. The Nmea0183Tester tool has "SetDefault" buttons that store the settings inside an "ini file" so that you do not need to change again a particular setting except if you need to modify a parameter. In the end the received file has the same content as the sent file. The video finalizes this post. I used the free tool EZVID that I downloaded this afternoon and therefore the video is not professional so to speak. I hope that in the future I will post "tutorial videos" to help users to understand better and easier the particularities of the multiplexers. Please see the video in full screen!